1. Field of the Invention
This invention relates to a stroller frame, and more particularly to a foldable stroller frame that is easy to unfold and fold.
2. Description of the Related Art
A conventional stroller frame includes a seat frame assembly, a plurality of tubes and plastic components. The tubes include a front leg tube, a rear leg tube, and a handle tube. Typically, the seat frame assembly is designed to allow a stroller seat or a car safety seat to be mounted thereon. A plurality of pivot pins are disposed for interconnecting the tubes to form a foldable structure. A locking mechanism is disposed between two of the tubes, and is operable to allow for unfolding and folding operation of the stroller frame.
Typically, the locking mechanism can be converted between locking and release states by operating a one-hand folding mechanism with one hand. The locking mechanism may include a locking member disposed movably within the handle tube, and a lock seat disposed on another tube, e.g., the rear leg tube. The locking member can be moved toward or away from the lock seat. When the locking member is released from the lock seat, unfolding and folding operation of the stroller frame is allowed. When the locking member is locked on the lock seat, unfolding and folding operation of the stroller frame is prevented.
However, the aforesaid conventional stroller frame has a disadvantage. That is, when the stroller frame is not in either an unfolded or fully folded state (i.e., is in a semi-folded state), if a load is applied to the seat frame assembly, e.g., as a result of climbing of an infant onto the stroller seat or the car safety seat, the handle tube and the rear leg tube may move toward each other, so that the stroller frame is overturned, which may cause damage to the infant.